Vapor resisting roof structure



Feb. 10, 1959 R; E. PAUL I ,87 ,8

VAPOR RESISTING ROOF STRUCTURE Filed May 13, 1954 INVENTOR. ROBERT E.PAUL BY J'' United States Patent VAPOR RESISTING ROOF STRUCTURE RobertE. Paul, Minneapolis, Minn., assignor to Minnesota and Ontario PaperCompany, Minneapolis, Minn.

Application May 13, 1954, Serial No. 429,561

' 2 Claims. ('Cl. 108-6) This invention relates generally tothermo-insulation and resisters to the flow of water vapors and inparticular to thermo-insulated water vapor resistant roof decks thatprovide a ceiling for the interior and a surface for receiving the roofstructure. 7

The problem of heat insulation between atmospheric air volumes ofdifferent temperature is complicated by water vapor in the air and bythe property of water vapor in air to condense at a precise temperaturedependent. upon the water vapor content. It is important to preventresulting damage to the roof insulating slab which furnishes thestructural element of the roof and the decorative surface for theinterior.

An important object of the invention is to provide a structuralinsulating unit adapted to take the place of roof boards now commonly inuse and at the same time provide a ceiling for the interior of thestructure and a roof receiving surface which may be safely used in anarea where the average January isotherm is below 45 F.

A further object of the invention is to produce a specific type ofstructural insulating member which provides water vapor resisters on alledges, which vapor barriers cooperate with vapor barriers on adjacentunits and which is shown and disclosed hereinafter.

For the purpose of this invention there has been elected to set forthcertain particular structures but it is to be understood that they arehere presented for illustrative purposes only and are not to be accordedany interpretation such as might have the efiect of limiting what isclaimed as the invention short of its true and comprehensive scope inthe art.

Other and further objects of the invention and the advantages of thesame will be pointed out hereinafter and indicated in the appendedclaims or will be obvious to one skilled in the art upon understandingof the present disclosure.

The drawing forming a part of the specification where:

Figure 1 is a view in side elevation of two slabs in nonassembledposition,

Figure 2 is a side elevational view of the two slabs shown in Figure 1is assembled relationship,

Figure 3 is a side elevation view of the two slabs showing thelongitudinal edge with the vapor barrier associated with the joint,

Figure 4 is a view similar to Figure 2 with a modified form of vaporbarrier on the abutting edges, and

Figure 5 is a perspective view with parts broken away showing the vaporbarrier along the edge and the end of the slabs.

An important feature of a roof slab made in accordance with thisinvention is that the roof goes up quickly and thus cuts the cost ofconstruction. A roof made in accordance with this invention from thestandpoint of comfort is effective in reducing heat transmission ineither direction. A building employing a roof deck made in accordancewith this invention will store up less heat in the summer which meanscooler interiors during the day,

2 and a quicker cooling of the house at night. During cold winters itwill result in the conservation of heat and thus reduce fuel costs.Before this invention a roof slab used to give a ceiling on one side anda roof receiving surface on the other could be used only in climateswhere the average January isotherm was not below about.

45 F. This was. due to the transmission of vapor into the roofstructure. It was found that in climates experiencing freezing weatherthat vapor in heated houses migrated into the insulation and below theroof structure and as it acquired a lower temperature, due to the vaporcondensing, it resulted in roofing difiiculties. Theoretically,condensation of vapors occurs at the dew point and at this point wateris deposited such as causes difficulty particularly in built up roofs.

In the layer of a roof structure the longitudinal edges are fittedsnugly together and the combination of the vapor resister along the edgein combination with the vapor barrier or resister placed adjacent theone side of the roof slab provides a substantially tight joint. Dueto-the necessity of spacing the end joints of each unit about /s" apart,a vapor resister must be furnished at these joints. Although such jointsoccur over beams, sufficient vapor will leak through the joint to causedifficulty particularly in built up roofs. I Referring to the drawingsin detail the roof slab indicated generally at 10 is composed of rigidfiber insulation board 12. Such board may consist of two or morelaminations. To the rigid fiber board 12 is secured a ceiling layer 14.This layer furnishes the finished interior surface of the house. Betweenthe board 12 and the layer 14 is vapor barrier 16. A suitable barrier isan asphalt saturated and coated paper, for example a 30-60-30 paper. Toprovide a suitable vapor barrier at the end of the unit which occursover beams the vapor barrier 16 extends from the end not less than A"and preferably about 1 in. or more to provide free ends. Each roof slabis provided along the longitudinal edge with a tongue 22 and on theopposed edge with a groove 24. It is to be understood, of course, thatvarious types of joints may be employed but regardless of the type ofjoint employed the grooves should be provided adjacent the tongue.

A suitable elastic gasket is preferred and a sponge rubber gasket by /2"has proven highly satisfactory. It is important that the gasket 26 inthe assembled slab contact the barrier 16 of the slab in which it ispositioned and the barrier in the adjacent slab. It is important thatwhen the slabs are assembled that the gasket be tightly compressed.Generally, each roof slab is considerably longer than it is wide and ithas been found that about 2 feet in width and about 8 feet in lengthgives very satisfactory results. In place of extending the vapor barrier16 beyond the ends of the slab as shown in Figures 1 and 2, the ends maybe formed together in overlapping joints as shown in Figure 4. If thistype of joint is used, it is preferred that vapor barrier material beplace in the joint as shown in Figure 4 at 28.

It is preferred that the ceiling portion of the slab be prefinished asby coating so that when applied a finished ceiling is provided. It is tobe understood that the ceiling facing portion 14 may be of the same orof diiferent material to the portion 12.

The roof slab may be applied as follows: start the application at thelower edge of the roof and work up the slope; applying the units withthe long dimensions at right angles to the framing members, leaving thetongue edge exposed; stagger the butt joint so that the adjacent piecedoes not end on the same framing member. It is necessary to bring thelong edges together to a snug fit. To accomplish this it may benecessary to use a driving Patented Feb. 10, 1959 block against theupper shoulder of the joint above the tongue. It is important that thegasket 26 in the long joint be tightly compressed before the unit issecured in place. To insurethis result, each unit. should be placed. inposition andbrought to a snugfit along the gasket edge and thenimmediately fasten the unit in place. The ends of the unit should beplaced 4;" apart and when the adjacent units are in position a vaporbarrier is provided at the ends as shown in Figure 2. It is notessential that calking material be used in the end joints but this jointmay be calked after the slabs are in position as shown in Figure 2. Itis to be understood that the built up roofs as well as other types maybe used in connection with the present invention.

What is claimed:

1.. The roof deck assembly comprising the combination of exposed beamsand a series of substantially rectangular insulating units securedthereto, each unit comprising a series of laminated fiberboard with aface board providing a finish ceiling surface, a vapor barrier membraneinterposed between two layers of the fiberboard, saidmembrane havingfree-ends extending beyond the end edges and contacting the ends ofspaced adjacent units and an elastic vapor barrier material positionedin a groove in the longitudinal edge of each unit and contacting thevapor barrier in adjacent units in the roof deck assembly.

. 2. A roof deck assembly comprising the combination of exposed beamsand a series of substantially rectangular insulating units securedthereto, each unit comprising a plurality of laminated fiberboard with aface board providing a finish ceiling surface, a vapor barrier membraneinterposed between the board providing the ceiling surface and theadjacent board, said vapor membrane having free-ends extending beyondthe end edges and contacting the ends spaced adjacent units and a vaporbarrier material positioned in a groove in the longitudinal edge of eachunit and contacting the vapor barrier in adjacent units and the assemblyroof deck.

References Qited in the file of this patent UN lTED STATES PATENTS OTHERREFERENCES Architectural Record, May 1954, pages 216-217.

